Spirit unfolds before revealing Mars secrets

NASA's Spirit rover has completed its "reverse robotic origami" in preparation for exploring the surface of Mars within days, much earlier than engineers had predicted.

The rover "now stands at full height and all six wheels are in their final position and ready to drive", said Jennifer Trosper, mission manager at NASA's Pasadena Jet Propulsion Laboratory.

The rover was folded into a compact form so that it would fit into the tetrahedron-shaped lander.

Unfolding it on Mars was "the most complex sequence of deployments that has ever been done on a robotic spacecraft", said Chris Voorhees, a mechanical systems engineer who devised the manoeuvre.

To allow the rover to stand up, 12 pyrotechnic devices had to fire, nine motorised mechanisms had to work, and six structural latches had to be engaged, he said.

Everything went perfectly. "She is asleep right now and resting on all sixes," he added.

Late on Saturday evening, engineers planned to move the instrument arm from its folded flight position to make it ready for travel on the surface.

Yesterday the team was due to fire a pyrotechnic device to sever the last cable connecting the rover to the lander, readying Spirit for roll-off on Wednesday. At that point, Ms Trosper said, "the lander becomes space debris".

The rover will then spend most of tomorrow pivoting 120 degrees to the right on the lander so that it can drive off on a secondary ramp. Mission engineers tried a simulated roll-off in their "sandbox" laboratory in Pasadena and concluded that there was a small chance that the rover's solar panels would brush against the bag if it tried to drive straight forward. "That's not really a place we want to be in," Ms Trosper said.

She noted that Spirit had transmitted more than 200 megabits of data back to Earth overnight on Friday, "10 times more than Pathfinder had the capability to do".

That data included another high-definition colour picture from the panoramic camera. The team hopes to have the entire panorama transmitted back to Earth "pretty darn soon," said geologist Matt Golombek.

The images obtained so far show that about 3 per cent of the site is covered by rocks, substantially less than the 20 per cent at the landing sites of the three previous missions to Mars. "It is also smoother and flatter than at least two of the three other landing sites, and it is less dusty as well," he said.